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May 19, 2015 - A Look At The New Commandlinefu
I've put together a short writeup on what kind of newness you can expect from the next iteration of clfu. Check it out here.
March 2, 2015 - New Management
I'm Jon, I'll be maintaining and improving clfu. Thanks to David for building such a great resource!

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Psst. Open beta.

Wow, didn't really expect you to read this far down. The latest iteration of the site is in open beta. It's a gentle open beta-- not in prime-time just yet. It's being hosted over at UpGuard (link) and you are more than welcome to give it a shot. Couple things:

  • » The open beta is running a copy of the database that will not carry over to the final version. Don't post anything you don't mind losing.
  • » If you wish to use your user account, you will probably need to reset your password.
Your feedback is appreciated via the form on the beta page. Thanks! -Jon & CLFU Team

extract email adresses from some file (or any other pattern)

Terminal - extract email adresses from some file (or any other pattern)
grep -Eio '([[:alnum:]_.]+@[[:alnum:]_]+?\.[[:alpha:].]{2,6})' file.html
2009-06-16 20:19:47
User: wires
Functions: grep
extract email adresses from some file (or any other pattern)

find all email addresses in a file, printing each match. Addresses do not have to be alone on a line etc. For example you can grab them from HTML-formatted emails or CSV files, etc. Use a combination of


to filter them.


There are 6 alternatives - vote for the best!

Terminal - Alternatives
grep -Eio '([[:alnum:]_.-]+@[[:alnum:]_.-]+?\.[[:alpha:].]{2,6})'
grep -aEio '([[:alnum:]_.-\+\-]+@[[:alnum:]_.-]+?\.[[:alpha:].]{2,6})'
2013-06-23 21:52:14
User: binarynomad
Functions: grep
Tags: grep email

This will catch most separators in the section of the email:

dot .

dash -

underscore _

plus + (added for gmail)

... and the basic dash '-' of host names.

grep -aEio '([[:alnum:]_.-]+@[[:alnum:]_.-]+?\.[[:alpha:].]{2,6})'
2013-05-30 07:17:32
User: nabil_kadimi
Functions: grep

The -a option in -aEio tells grep to treat binary files as text files.

Know a better way?

If you can do better, submit your command here.

What others think

I noticed none of these catch the '+' that is allowed in Gmail addresses:

[email protected] can freely add a plus and any word afterwards ([email protected]) and it is considered valid.


Comment by binarynomad 173 weeks and 6 days ago

People really should take the time to read RFC822 and RFC1035.

This regex is too limited in the username (e.g., plus signs are valid) and is simultaneously too permissive and too limitedin the domain name (underscores are not valid; dashes are and gTLD's can be longer than 6 chars).

To see how insane it is to try and create a single regex that correctly validates RFC822-compliant email addresses, here's one: http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html

I'd rather see a regex that was too permissive in the username and correct in the domain name. That way it's more likely to catch valid email addresses and bypass false positives.

Comment by KlfJoat 130 weeks and 1 day ago

Your point of view

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